Sewers and Scientific Thought

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This short summary of the relationship between waste management and scientific understanding was written as part of a competition entry entitled "The Sewer is [a] Mine." The complete project is available here.

Nineteenth Century: Miasmic Theory

In the 1850s sewers were state-of- the-art. At this time the predominant understanding of illness was miasmic theory — the idea that disease was caused by foul or corrupt air — a legacy of Greek and Medieval medical thought, passed down from Hippocrates and Galen to Renaissance and Enlightenment thinkers [1]. The solution to the sanitary problems of burgeoning cities, according to miasmic theory, was to prevent bad air by evacuating waste from the city and diluting it in running water [2]. The sewers of Paris and London, marvels of nineteenth-century engineering, promised to clean the city by dumping raw sewage into their waterways.

Germ theory, developed by Louis Pastuer in the 1860s and Robert Koch int he 1870s, cast doubt on this strategy. Outbreaks of cholera in London were linked, controversially, to waterborne illness by Dr. John Snow in the 1849. But by the time germ theory gained wide acceptance, sewer systems has already been constructed in most European and American cities.

Pierre Patte's famous proposal for a modern sewer system, circa 1769. Patte's designs proved highly influential to nineteenth century planners and engineers.

Twentieth Century: Germ Theory

The sewers, rooted in miasmic theory, made no distinction between wastewater and stormwater (based upon the mistaken belief that once waste was diluted it was effectively treated); thus retrofitting the sewers proved difficult. The germ-theory-inspired waste treatment facilities, affixed like filters to the end of the pipe, assuaged the worst of the human health concerns, but were not sized for major rain events. Today, major North American cities from Vancouver to Cincinnati regularly discharge sewage into local waterways [3] — a legacy we owe, ultimately, to miasmic theory.

Combined sewer and stormwater systems serve roughly 772 communities throughout the United States (image from the US EPA).

Twenty-first Century: Biology & Ecology

Since the installation of sewage treatment facilities, biological and ecological sciences have continued to illuminate the myriad effects of sewage — even treated sewage — on human and ecological health. PCBs, endocrine disruptors, heavy metals, and phosphates are routinely discharged into waterways, with mounting negative consequences [4]. Treatment facilities — rooted in the science of germ theory — were not designed to remove these contaminants.

What is the waste system that will be inspired by the new science of ecology? Can it be applied as a band-aid fix to existing infrastructure — that lingering built expression of Medieval science? Or does it require something else entirely?

Architect William McDonough and chemist Michael Braungart propose a cradle-to-cradle paradigm in which "waste equals food," flows are cyclical, and toxins are designed out of the system from the outset [5]. This paradigm recognizes both the human health impacts illuminated by germ theory and ecological understanding of the twenty-first century. What will a no-waste, 100% good, cradle-to-cradle waste system look like? This is our challenge.

Proposed wastewater treatment system that mines combined sewers and utilizes biodigesters and artificial wetlands to treat wastewater and produce energy, fertilizer, food, and water. Image from "The Sewer is [a] Mine" competition entry.

[2] Carlo M. Cipolla, Fighting the Plague in Seventeenth-Century Italy (Madison: University of Wisconsin Press, 1981). See also Leon Battista Alberti's On the Art of Building in Ten Books (1450), which was oft cited by Enlightenment thinkers.